Trunked communication systems are known to comprise a plurality of communication units, a limited number of communication resources that are transceived via a predetermined number of repeaters, or base stations, and a communication resource allocator that allocates the limited number of communication resources among the plurality of communication units. The communication units may be portable radios and/or mobile radios. The communication resources may comprise a TDM (time-division multiplexed) bus, a carrier frequency, a pair of carrier frequencies, or any RF (radio frequency) transmission means.
In many systems, the communication resource allocator for each coverage area is a distributed infrastructure connected to each of the repeaters via a local area network. One repeater is designated as an active resource controller, also called an active master, which allocates communications resources for all requests in the coverage area via the local area network. Although only one repeater maintains this function for a coverage area, two or more, perhaps even all, repeaters in each coverage area are capable of performing as the active resource controller, in case a repeater goes down for service or some other reason. When the active resource controller goes down, the remaining repeaters choose a new active resource controller, and communications continue.
If the local area network develops a break, thus separating the active resource controller from any number of repeaters, the separated repeaters choose a new active resource controller, thus two active resource controllers and hence two systems exist for the same coverage area. This will cause turmoil in resource allocation, because both controllers may allocate the same resource to different users at the same time, or allocate different resources to the same user for one call. Further difficulties arise when a group call must be established, as some units from a group may be assigned to one system, and other units from the same group may be assigned to the other system, resulting in group members missing group calls. Many other undesirable communication trouble may result when a single system splits into two separate systems. Because this situation must be avoided, a method of reestablishing unified control of the resources on both sides of the break in the local area network is required.